1. Technical Field
The present invention relates to a disc picking device which picks a disc by an engaging member. More specifically, the invention relates to a disc picking device capable of appropriately performing the operation of picking the disc without incurring any disc damage or engaging defection of the engaging member and a disc processing apparatus having the disc picking device.
2. Related Art
In a disc processing device such as a disc dubbing device, which writes data in multiple discs such as blank CDs and a CD/DVD publisher which can publish a disc using a produced disc by writing data and printing a label, generally, multiple blank discs or recorded discs are loaded into a stacker such that the discs are stacked in a thickness direction. Gripping devices for gripping a disc loaded in a stacker including a configuration in which a disc is gripped by inserting three gripping claws into a center hole of a disc and expanding the gripping claws in a relative diameter direction of the center hole to push the inner circumference face of the center hole are known.
In Patent Document 1 (U.S. Pat. No. 6,802,070), a CD transporting device is disclosed. In this CD transporting device, a disc is gripped by inserting three gripping pieces (gripping portion) into a center hole of a CD and expanding the gripping pieces in a radial direction to push the inner circumference face of the center hole.
In order to expand the three gripping pieces in the radial direction, two gripping claws are fixed, and the remaining one gripping piece is moved in a direction away from the two gripping claws, thereby increasing the area of the circumscribed circle of the three gripping pieces.
In an arm to which the gripping pieces are attached, a position sensor for detecting a surface of a CD is disposed, and the insertion of the three gripping pieces into the center hole of the CD is detected based on the output of the position sensor.
When insertion of the gripping pieces into the center hole of the disc cannot be precisely detected by the position sensor, there is a possibility that a problem such as a gripping defection and disc damage occurs. For example, when the insertion of the gripping pieces is detected before the gripping pieces are sufficiently inserted into the center hole of the disc due to a manufacture error of the gripping piece, the arm, or the like, due to an attachment error of the position sensor to the arm, or due to a detection error of the position sensor, and the like, so that the insertion is stopped, the disc is not assuredly gripped by the gripping pieces, and accordingly, the disc may fall down while being transported. On the other hand, when the detection of the insertion of the gripping pieces is late, a part such as a hub to which the gripping pieces are attached may collide with an edge portion of the center hole of the disc causing damage the surface of the disc, and in some cases, there is a possibility that the disc is destroyed.
Accordingly, the non-uniformity of the stop position of the gripping pieces caused by the position sensor needs to be eliminated. It is very difficult, however, to remove the non-uniformity of a normal position of the gripping pieces caused by manufacture errors and attachment errors of the components, a detection error of the position sensor, and the like.
In Patent Document 2 (JP-A-2003-331479), a clamper base (contact portion) contacting an upper face of a disc is supported to be rotatable with respect to a bracket (arm) lifted by a lifting mechanism in a direction opposite to the insertion direction, and an upper face of the uppermost disc of a disc storage portion is pressed by a spring force of a torsion spring after the clamper contacts the upper face of the disc.
However, according to the technology disclosed in Patent Document 2, a rotating mechanism should be provided in the bracket to make the bracket thick and heavy, and consequently, the technology is not appropriate for high-speed transport of a disc.